1. Field of the Invention
This invention relates to a particle analyzing apparatus for applying a light beam to a particle to be examined, photometering light emitted from the particle to be examined and analyzing the particle to be examined, and in particular to a particle analyzing apparatus for calculating the particle diameter of said particle to be examined from scattered lights emitted from said particle to be examined.
2. Related Background Art
In a conventional particle analyzing apparatus used in a flow cytometer or the like, an irradiating light is applied to sample liquid such as corpuscle cells wrapped in sheath liquid and passing through a circulating portion at the center of a flow cell which has, for example, a minute rectangular cross-section of 200 .mu.m .times.200 .mu.m, and the resultant forward scattered light, sideways scattered light and fluorescent light are photometered to find the particulate properties such as the shape, size and refractive index of a particle to be examined, thereby accomplishing the analysis of the particle to be examined.
In FIG. 10 of the accompanying drawings, a particle S to be examined passes through a circulating portion 2 at the center of a flow cell which is perpendicular to the plane of the drawing sheet, and a laser source 3 is disposed in a direction orthogonal to this flow. On the optic axis 0 of the laser beam L emitted from this laser source 3, there is disposed an imaging lens 4 comprising two sets of cylindrical lenses orthogonal to each other disposed adjacent to the laser source 3 with respect to the particle S to be examined. Also, on the optic axis 0 on that side opposite to the laser source 3 with respect to the particle S to be examined, there are successively arranged a light-intercepting plate 5, a condensing lens 6 and a photoelectric detector 7. The output of the photoelectric detector 7 is connected to an operation circuit 8.
The laser beam L emitted from the laser source 3 is shaped into an imaging beam of any long or short diameter by the imaging lens 4 and is applied to the particle S to be examined flowing through the circulating portion 2. The laser light L which is not scattered by the particle S to be examined is prevented from rectilinearly travelling by the light-intercepting plate 5, and of the scattered lights scattered by the particle S to be examined, the forward scattered light is condensed on the photoelectric detector 7 through the condensing lens 6 and the properties of the particle S to be examined are measured. That is, generally, the forward scattered light detecting intensity corresponds to the particle diameter, and from this scattered light detecting intensity, the particle diameter can be calculated in the operation circuit 8.
However, in this example of the prior art, as shown in FIG. 11 of the accompanying drawings, the relation between the scattered light detecting intensity and the particle diameter is not a always increasing function, that is, the scattered light detecting intensity and the particle diameter is not in the relation of 1 to 1, when the particle to be examined is of a light-transmitting property, and this leads to the problem that measurement cannot be done in the vicinity of a certain particle diameter.